Prior art Multi-Ration Heater (MRH) 1 (manufactured by TRI Tech USA, Inc. with offices in 3 Green Tree Drive, South Burlington, Vt. 05403) has been developed for the US Army Soldier System Center in order to provide military personnel with a hot meal in the field (see FIGS. 1A-1C). FIG. 1A shows a side view of MRH 1, FIG. 1B shows a top view of MRH 1, and FIG. 1C shows a front view of MRH 1. MRH 1 is capable of re-thermalizing eighteen tray packs 5 of food in 30-45 minutes. MRH 1 is equipped with 15 gallon tank 2 for holding water, which is heated by a Diesel or JP-8 fired burner 3 manufactured by R. W. Beckett Corp. The burner includes a fuel pump and a blower both powered by alternating current supplied by liquid-fuel burning electric power generator 6. The burner is adjacent to firebox 4 of MRH 1. Tank 2 is preferably fabricated from stainless steel. Also, the bottom of tank 2 is approximately 1/16 inch think stainless steel and serves as the top of firebox 4. Hot exhaust from the burner passes under tank 2 and passes tank 2 sidewalls and exits through exhaust manifold 19. As it passes under tank 2 and next to the sidewalls of tank 2, the hot exhaust heats the water to boiling at approximately 100° C. The boiling water produces steam that re-thermalizes tray packs 5. Control box 7 is utilized for controlling burner 3. MRH 1 also includes thermal insulation 13.
MRH 1 is portable can be installed on the back of a vehicle as a heat-on-the-move concept. MRH 1 is capable of starting and trouble-free operation at temperatures ranging from −32 to +49° C. MRH 1 is manufactured of stainless steel, so field environment (rain, mist, snow, etc.) does not cause any corrosion problems. A sensor automatically shuts off the burner if the water tank level drops below a minimum allowable level of 1.5-2.5 inches. Burner 3 requires about 200 Watts of electric power for steady state operation. The generator requires maintenance, is noisy, and increases the weight. Also, the generator adds complexity to operation of MRH 1.
Thermoelectric devices are well known and have been commercially available for about 30 years. One such module is described in U.S. Pat. No. 5,892,656 that is incorporated herein by reference. The module described in that patent includes 98 couples. Its dimensions are 2.5 inches×2.5 inches×0.2 inch and with a temperature difference of 360° F. (200° C.) will produce 14 Watts at 1.65 volts. Hi-Z also makes a 20 Watt module as Model No. HZ-20 that produces a nominal 20 Watts with a 200° C. temperature difference (with Tcold at 30° C.) and about 11.3 Watts with a 150° C. temperature difference.
What is needed is a self powered ration heater that is capable of re-thermalizing tray packs and simultaneously generating electricity that is sufficient to run itself.